Hospital Acquired Infections, like CAUTI, cause unnecessary suffering and should be prevented

Hospital Acquired Infections remain a major challenge in today's healthcare

While proper hygienic procedures will lower the incidence of infections keeping bacteria from entering catheters completely seems almost impossible. When microorganisms enter a device, such as a catheter, bacteria may adhere to the material leading to the formation of what is known as a biofilm. BIofilm formation poses serious problems in the clinic as the biofilm often contains several different cell types. Antibiotic resistance is common in biofilms as the microenvironment in the film promotes genetic transfer. Often the cells in the biofilm will eventually cause an infection in the patient. Hence developing materials resistant to biofilm formation has been a goal in the development of medical devices for many years. Unfortunately without breakthrough results so far.

Catheter Associated Urinary Tract Infections (CAUTI)

Catheter Associated Urinary Tract Infections (CAUTIs) are the most common form of hospital acquired infections - HAIs - with more than 560,000 cases/year estimated in the US alone CAUTI is also the leading cause of secondary bloodstream infections. Infections are typically associated with the use of indwelling catheters – Foley catheters. When a catheter is inserted in the urethra, the catheter may carry microorganisms both into the lumen of the tube and into the space between the catheter and the urethral mucosa. Unlike in the non-catheterized urethra where organisms are eliminated efficiently, bacteria can multiply to high concentrations in the catheterized urethra and eventually leading to biofilm formation in the catheter and sometimes even in the drainage back. Bacteria from the biofilm may eventually move into the bladder. This is what causes the infection – either as asymptomatic bacteriuria or as a symptomatic infection. (Warren JW, International Journal of Antimicrobial Agents 2001). The most important risk factor for the development of CAUTI is the duration of catheterization. 10-50% of patients undergoing short-term catheterization - 7 days - develops CAUTI compared to almost everyone catheterized for more than 28 days. (Stickler DJ, Biofouling 1996).

Biofilm formation in catheters and medical tubing causes infections

While proper hygienic procedures lower the incidence of infections, keeping bacteria from entering indwelling catheters completely seems almost impossible. When microorganisms enter a device such as an indwelling urinary catheter, cells may adhere to the material leading to the formation of what is known as a bacterial biofilm. Adhesion to catheter materials, like silicone medical tubing, is strongly related to the hydrophobicity of the material (Brisset L, et al, Pathol Biol 1996). The formation of biofilm poses serious problems in the clinic as the biofilm often contains several different cell types. Antibiotic resistance is common in biofilms as the microenvironment in the film promotes genetic transfer (Roberts A, et al, Microbiol Lett 1999). Often the bacteria in the biofilm will eventually cause infection in the patient. Biofilm formation often results in precipitation of minerals that can form encrustations that may eventually block the lumen of the catheter or make the removal of the catheter very painful (Tunney MM, et al, Methods in enzymology 1999). Hence developing materials for medical tubing resistant to biofilm formation has been a goal in the development of medical devices for many years. Unfortunately without breakthrough results so far.

Questions about biofilm

Can biofilm make you sick?

Yes. The formation of biofilm on medical devices is believed to be one of the main causes of infections. In fact, if you could minimize biofilm formation in catheters you could probably significantly lower infection rates.

Are biofilms sensitive to antibiotics?

Depending on the strand of bacteria forming the biofilm it will often require significantly higher concentrations of antibiotics to eliminate biofilm than to inhibit planktonic growth.

Are biofilms resistant to antibiotics?

Resistance can quickly evolve in the microorganisms forming the biofilm. One reason is that the microenvironment favors genetic transfer. This makes it very difficult to eliminate biofilms. You can read more here.

Can biofilms be composed of multiple species?

Yes. In fact, most biofilms contain multiple species of bacteria. This is one of the things that can promote the spreading of antibiotic resistance and make it difficult to treat. Read more here.